The invention relates to a fuse device and, more particularly, to a fuse device for a cable in motor vehicles with a current strength sensor, an evaluation circuit connected downstream of the current strength sensor, and a severing device for severing the cable at a current strength that lies above a limiting value.
A known fuse device is described in German Patent document DE 41 10 240 C. The sensor, evaluation circuit, and severing device are spatially separate from one another. The sensor is located above an exposed portion of the cable separate from the severing device. Separate lines run between the sensor and the evaluation circuit on the one hand, and between the evaluation circuit and the severing device on the other hand. The design of the known fuse device is therefore expensive and especially prone to problems that can disadvantageously occur in the especially critical case of an accident. The connecting leads between the sensor and the severing device and the evaluation circuit are exposed to the risk of damage or destruction. This can lead to an ineffectiveness of the known fuse device at precisely the time of a critical situation such as an accident as mentioned above.
There is therefore needed a fuse device of the abovementioned type such that it is characterized by a simple design and high effectiveness.
These needs are met according to the present invention by fuse device for a cable in motor vehicles with a current strength sensor, an evaluation circuit connected downstream of the current strength sensor, and a severing device for severing the cable at a current strength that lies above a limiting value. The sensor, evaluation circuit, and severing device are located in a housing in which a section of the cable also runs.
Advantageously, the compact design of the fuse device according to the invention means, first of all, that there is no danger of its destruction, especially in an accident. At the same time, the design results in a definite reduction, if not complete elimination, of functional problems, specifically during an accident. The fuse device can be located at any point, for example directly behind or integrated with the positive terminal of a vehicle battery, or directly behind or integrated with a battery support. The compact design of the fuse device also influences the cost. In contrast to known fuse devices, there are definite cost advantages which make it possible to use the fuse device in a multiple manner in a cable to monitor for example a plurality of line sections that are especially at risk.
Advantageous embodiments of the invention are characterized by: 1) further reduction of the wire cost; 2) the possibility of replacing the fuse device after the severing device has operated, without performing extensive repairs on the cable for that purpose; 3) the possibility of performing this repair in an especially prompt and inexpensive manner; 4) further reduction in the size of the total structure and, hence, in the manufacturing costs; 5) achieving a further cost reduction by multiple use of the current sensor; 6) an additional possibility of replacing the fuse device without great expense; 7) when the current load is high as a result of operation, the possibility of preventing activation of the severing device (typically when starting an internal combustion engine); and 8) the possibility of adjusting the triggering threshold for the severing device to the changing current loads on the cable.
The possibility of adjusting the triggering threshold for the severing device to the changing current loads on the cable offers a wide variety of possibilities. Thus, it is not only possible to take into account load fluctuations occurring in rapid sequence and to quickly modify the triggering threshold for the severing device, but also to take into account loads related to operations that vary from one vehicle to another, and which are caused, for example, by the use of different electrical consumption devices. It is also possible to take into account a change in the current load that occurs during long-term operation as the result of slowly changing electrical properties of various electrical consumers. Such a phenomenon is comparable with long-term drift and can be recognized, for example, by differentiation of the current changes, for example in addition to or directly during defined loads on the cable.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.